Group 41, a San Francisco based architecture and design firm, has developed a reputation for its attractive, eco-friendly creations.

Joel Karr, founder and owner of Group 41, spent 18 years working in commercial design and wanted to branch out into different types of projects, including modern residential design.

"My focus was to move away from the large-scale corporate commercial work I had been doing and move into more of a boutique, high-design market space," Karr said.

Karr has added a unique twist to many of his projects by repurposing the shipping containers used on freight liners into building materials. While living in Japan 15 years ago, Karr saw an opportunity to turn wasted freight containers into something more useful, an idea that he has been developing ever since.

One of the most distinctive examples of this design is H House, a modernist, eco-friendly home unveiled in 2009 which used shipping containers for many aspects of its construction.

Karr has overseen a wide variety of projects, but he has a preference for contemporary works.

"My passion is for ultra-modern and challenging eco-friendly designs," Karr said. "That's really the focus of what I do. All architects take projects that maybe don't align precisely with the ideal nature of their own aesthetic, but in general, that's the work that I'm trying to do."

While Karr said many extra-large homes can at times conflict with environmental ideals, he said that he does everything in his power to mitigate the negative impact caused by the constructions.

"The shipping container work is by its nature an ultra-green approach to building," Karr said. "It uses completely prefabricated and up-cycled shipping containers. We have also been using highly sustainable materials and sustainable building systems."

For the H House, which is a large, single-family home, Group 41 used solar-ready and efficient heating and cooling systems and the latest materials to complement the building's modern contemporary design.

While Karr's love of the modern is perhaps the most defining element of his work, he and his firm also pay close attention to the historical significance of their projects. In one of Group 41's recent projects, the team was able to renovate an old, historic Italianate home's exterior while redesigning the interior into a completely modern, energy-efficient living space.